The present invention relates to a connecting terminal having a housing in which a lift cage is arranged, with the housing and the lift cage each having a first opening which can be aligned such that it is flush, for inserting a cable end into the lift cage.
Such connecting terminals are generally known, and are illustrated in the form of a specific embodiment in FIGS. 1A,1B ,2A ,2B.
Against the background of other connecting terminals which are known from the prior art and are mounted by means of at least one solder pin per pole on the board of an electronic circuit, these connecting terminals form an improvement with regard to mechanical and electrical reliability. In FIG. 1A, the reference number 10 denotes a circuit board having one or more layers, or a busbar. Openings 12a,12b are provided in the circuit board 10. Two screws 16a,16b are recessed in the housing 14.
FIG. 1B shows a section along the line Axe2x80x94A in FIG. 1A. This shows the opening 12b in the circuit board 10 and the screw 16b, which is recessed in the housing 14 and presses against a solder pin 18 which is formed in a meandering shape. The housing 14 has an opening 20 for inserting a cable end 24 (see FIG. 2B). Arranged in the housing 14 is a lift cage 22, which can be moved relative to the housing 14 by rotating the screw 16b. Located in the lift cage 22 is an opening 21, which can be aligned with the opening 20 of the housing 14 such that they are flush.
FIGS. 2A and 2B correlate with the illustrations in FIG. 1A and FIG. 1B, although a cable end 24 has now been inserted into the opening 20 in the housing 14 and into the opening 21 in the lift cage 22, the solder pin 18 has been inserted into the opening 12b, and has been fixed in this position by means of solder 26. The cable end 24 is nowxe2x80x94once the lift cage 22 has been moved upwards by rotation of the screw 16bxe2x80x94conductively connected to the solder pin 18. The solder pin 18 is in turn conductively connected via the solder 26 to a conductor track 28 on the circuit board 10. The meandering shape of the solder pin 18 increases the torsional elasticity and thus avoids stressing the solder point.
Against the background of this prior art, the present invention is based on the object of developing a connecting terminal of this generic type in such a way that the electrical resistance caused by the solder point is reduced.
This object is achieved by a connecting terminal having the features of Patent Claim 1. Since the housing and the lift cage have a second opening which can be aligned such that it is flush, and through which at least one part of a circuit board can be inserted into the lift cage, this makes it possible for a conductor track on the circuit board to be pressed conductively against a cable end by means of a different point on the lift cage. Since there is no need whatsoever for any solder pin, the production costs are reduced. Since there is no longer any need to carry out any soldering, the electrical resistance of the solder point disappears completely.
In order that a part of a circuit board can be inserted into the connecting terminal, it is particularly advantageous for the circuit board edge to be shaped in the form of a finger. This configuration and the fact that the terminal housing projects at right angles between a number of such fingers of the circuit board result in the air gap and creepage distances, and hence the withstand voltage between the individual poles of the terminal, being increased in an advantageous manner, where a number of individual terminals according to the invention are combined in a common housing. The connecting terminal is in this case advantageously made of insulating material.
In one particularly advantageous embodiment, the first and the second opening in the lift cage are designed, and connected to one another, and these two openings merge into one another, in such a way that a conductive connection can be produced between the cable end and a conductor track on that part of the circuit board. The lift cage can be moveable with respect to the first and the second opening in the housing, in particular by rotation of a screw, in such a way that the conductive connection between the cable end and the conductor track can be fixed. Alternatively, the mobility of the lift cage can be provided by a spring, which is located in a first position for inserting the circuit board and the cable end, and is located in a second position for fixing the cable end and the circuit board. To make operation easy, it has been found to be advantageous to arrange the first and the second opening on diametrically opposite sides of the housing and of the lift cage. However, a particularly robust embodiment results if the first and the second opening are arranged on the same side of the housing and of the lift cage, in particular being formed by a common opening.
To improve the fixing of the connection between the circuit board and the housing, the housing may have latching means which interact with the circuit board. In particular for relatively weak circuit board material, it is possible to provide, in order to produce a conductive connection between at least one part of the circuit board and a connecting terminal according to the invention, that a U-shaped crushing protection device can be pushed over that part of the circuit board which can be inserted into the connecting terminal in order to produce a conductive connection to the cable end.
The crushing protection device may in this case have a tilting protection apparatus which prevents tilting of at least that part of the circuit board which is inserted into the connecting terminal. A projection in the housing of the connecting terminal can interact with a cut-out in the crushing protection device for this purpose. A projection on the crushing protection device and a cut-out in the connecting terminal which interacts with it have the same effect, of course.
The crushing protection device can be produced from an electrically conductive and/or resilient material and may have latching means which interact with the housing in order to fix the crushing protection device in the housing.
The invention also comprises a circuit board for use with a connecting terminal according to the invention or for use in a system comprising a connecting terminal according to the invention and a crushing protection device, in which case the circuit board has at least one projection which is in the form of a finger and can be inserted into the connecting terminal in order to produce a conductive connection to a cable end. The projection which is in the form of a finger may have latching means which interact with the latching means on the housing of the connecting terminal. It may also have a tilting protection apparatus, which prevents tilting of the projection, which is in the form of a finger, in the connecting terminal.
Further advantageous developments of the invention are defined in the dependent claims.